Failing Limitations
by xRae Asakurax
Summary: Okay, so maybe EVOs can go on for a lot longer without getting exhausted. But even Rex has his limits, and Ben wants to know why he hasn't reached them yet when he looks like he's gone shooting straight past them. R/B, light slash. One-shot.


**Rae:** Am I REALLY the only one to see the potential for this pairing? SERIOUSLY?

As much as I love the Ben/Dexter stuff, for some reason Rex/Ben has made it further into my OTPs than B/D. Thus, I'm giving this pairing some much needed love.

Even if it's nothing like my best work. At all

Ah well, Enjoy anyway! I don't own Generator Rex, Ben 10 or FusionFall!

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><p>Ben paused as he passed the hallway leading to the training rooms, ears just catching the sound of machinery so faint he would have missed it if he hadn't been taking in his surroundings. A glance at the timepiece attached to his Omnitrix told him it was 2:47 in the morning. And nearly time for him to finish his rounds before next watch was up.<p>

After all, they had to be vigilant at all times while Fuse and his Flubber rejects were around. Especially at DexLabs.

Still, it was well past curfew for most other people, who would all be asleep trying to catch up on the rest that eluded them otherwise. Curiosity got the better of him, and he absently radioed Numbuh 486 to tell him he was checking something out in the training grounds. A worried _'alright, but be careful' _went unheard by the teenager as he began a meander past the sixteen TRs, peering into the operating room of each to see where the machinery noises were coming from and why they were there.

It wasn't until he reached TR 11 that he found his answer, and it certainly wasn't what he was expecting. Stepping into the operating room gave him a clear view of the gym below it, and standing in the middle of said room with his legs halfway twisted in mid-transformation and seemingly stuck like that was Rex Salazar.

Ben eyed the older boy as he gave up the transformation endeavour with a loud, "maldito!" and created one of his SmackHands right before his fist connected with the wall. For someone who had been on the front lines the past three days in a row with barely any time to rest up or recover, Rex was looking remarkably spry. Despite dark circles haunting mahogany eyes the Evo practically vibrated with energy, though whether from adrenaline or sheer frustration Ben wasn't sure.

As it was Ben had noticed something off about Rex, and from the looks of it something still was. It had been going on for somewhere around a couple weeks, and got to the point that even Dexter had quietly pointed it out to him one evening while they were working together. As the boy genius had mentioned it - and he was renowned for only mentioning bad things about his colleagues if he was worried for them - it had erased all doubt in the Omnitrix wielder's mind that it was just his imagination.

Sighing Ben left the operating room and went to the bay doors sealing off the training room. He ran his ID through the sensor and it flashed green in acceptance. Ben briefly wondered how Rex had got in without a keycard, but then remembered the older boy was a technopath thanks to his nanites, and he'd probably just hacked his way in. The door slid open with a silent hiss, revealing Rex in mid-change once again. His face was scrunched up with frustrated concentration, before he gasped and let his body go limp, the half-built construct melting away into his body. He doubled over, hands on his knees and breathing heavy.

"Rex?"

The sound of his name brought the Evo out of his own world and his Battle Axes into Ben's, but they quickly disappeared once Rex realized who it was.

"¡Mierda, Ben! Don't sneak up on me like that!" Rex gave him a look and moved to the wall so he could lean against it. "What on earth brings you here?"

"I could ask you the same thing," countered Ben, putting a hand on his hip and cocking an eyebrow at the Hispanic boy. "Why aren't you resting? You've been out pretty much non-stop for three days. There's only so much you can take before you succumb to exhaustion."

"I know." Rex looked away, arms crossing his stomach in an uncertain gesture. "I know, Ben."

"So?"

"I can't sleep," was the quiet answer. "I don't know why. I haven't slept for the past week and a half, never mind three days."

Frowning, Ben walked up to Rex and placed the back of his hand briefly on a tan forehead, then took one of the older boy's hands. "No fever, and your hands feel fine. Not clammy or cold."

"I'm not ill." Rex dropped his other hand to the brunette's forearm. "I should be, but I'm not. I should be exhausted, passed out somewhere. I should be feeling drowsy, weak, sluggish."

"So... what, you're trying to drive yourself into that state, force your body to rest?"

"Sí. I should not have this much energy, Benji. I shouldn't be able to still go on. I want to sleep, to rest, recover, _Lord_ knows I do."

"But you can't." Ben canted his head to one side, then abruptly tugged at the hand he still held and started dragging Rex out the room. "C'mon, we're gonna find out what's going on."

"Oh no!" Rex wrenched his hand out of Ben's and held it to his chest as though he'd been burned, eyes wide and hard. "No, Ben, there is no way I'm letting Holiday know about this."

"I wasn't thinking of Doctor Holiday," was the patient reply. "I'm talking about Dexter. He'll keep a lid on it, and Providence out of it if needs be. He can help, Rex, I know he can."

"I-" Rex stopped, looked down at himself and then sighed. "Alright alright. But damn it, if Six or Holiday ever get wind of this I won't be left in peace for a moment. It was bad enough when Six grounded me because I couldn't use my nanites properly."

Ben just grinned and tugged at Rex's jacket, pulling him along once more and calling in to Numbuh 486 that it was just a night owl getting some training done.

**-x-**

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><p><strong>-x-<strong>

"I'm sorry for dragging you out of bed, Dex, but I'm not sure this can wait."

"It's okay," the red-head yawned, rubbing at his blue eyes and replacing his glasses. "That's the longest sleep I've had in a while, I'll be alright. Mr Green will be pleased, at least. Now, what's so urgent you need me to look at?"

"It's Rex," said Ben as they padded hurriedly towards one of Dexter's smaller labs where Ben had put the Evo and told him to wait. "He hasn't slept in over a week, but he's showing no signs of exhaustion or lethargy. It's really weird. I was hoping you could take a look, see what you thought. And... keep it on the down-low. He's terrified of Six or Holiday finding out about this."

"Benjamin," reprimanded Dexter lightly, "you of all people should know discretion is my forté."

I know, I know," the brunette said, throwing his hands up momentarily in surrender. "Just making sure you do."

They reached the lab and the doors hissed back to show Rex sat on one of the tables (thankfully cleared) swinging his legs back and forth agitatedly. He looked up when they entered, deep rich mahogany eyes meeting worried acid green before sliding down to meet the professional curiosity of one Dexter McPherson.

"Hey," was all the Hispanic boy said.

"Mr. Salazar," Dexter greeted as he eyed Rex critically, apparently deciding what to do. He eventually moved to collect a large red box under his bench, bringing it up onto the table next to the Evo and opening it. Taking out a blood pressure gauge he wrapped the band neatly around Rex's left upper arm, making sure the sensors were in the right places and the wire had no kinks, and pushed gently at him to rest it at chest level on the table and pressed one of the buttons on the pad.

Immediately Rex felt the uncomfortable pressure of the band as it inflated, and the red-head pushed another button. The band stayed inflated for a few seconds, then deflated almost as fast. Dexter let him unwrap the band as he took in the reading, and instantly stared at the Hispanic boy in shock.

"Mr Salazar-"

"Rex," the Evo cut in, rubbing at his arm.

"-Rex," conceded Dexter, "your blood pressure is 181 over 115. That's not normal; you're in hypertensive crisis. You're coming with me immediately, this is beyond my capabi-"

"Wait, wait, wait," interrupted Rex once more, waving both hands at Dexter. "My blood pressure's always been higher than that of a normal human. On average I think Holiday said mine was about 158 over 97. Because of the nanites, I think; they take up room so my blood vessels expand to compensate. So yeah, it's high for you, but only slightly higher for me."

Dexter looked at him with a raised eyebrow. "Interesting," he said, with a tone that suggested genuine fascination. "What other abnormalities do you have medically?"

Rex listed as many as he could remember from Holiday's "geek-outs"; high iron count, low breathing and heart rates, high concentration of oxygen, very high immunity but low white blood cell count...

The list went for a little bit longer as both Ben and Dexter absorbed the information like a pair of sponges, though each for different reasons. Afterwards Dexter tested for as many as he could based on the averages Rex had given him, but couldn't find anything abnormal aside from the ridiculously high blood pressure.

"I wonder," the red-head mused out loud a while later, "if it's something psychological or mental rather than physical."

"What do you mean?" asked Ben, confusion flitting across his face.

"From what I've learnt about Rex's nanites from Doctor Holiday, they can react to his emotional or psychological state. Am I correct?" He aimed the last question at the Evo, who looked momentarily startled but nodded sheepishly. "Then perhaps we're over-looking the obvious. Have you any severe emotional upheavals or been under any kind of mental duress lately, Rex?"

"Umm..." The black-haired youth considered for a few minutes, chewing on his bottom lip in a way that just seemed to shred any doubts about whether Ben was attracted to the Evo. "I don't think so. No more than usual, anyway."

"Nothing at all?"

"Nada." Rex chewed his lip a bit more, then his mahogany eyes widened almost comically. "Oh, wait! Maybe that's it!"

"Care to share with those of us who aren't telepathic, Rex?" said Ben with a grin, and Rex poked in tongue in the brunette's direction.

"What I mean is, a couple weeks ago I was in a battle with two of the Fusions; Buttercup and Samurai Jack, I think. It was a really hard fight, those two don't give up easily." He gave Ben a nervous side-long look, as though he were hesitant about carrying on. "I... one of my friends got hurt, a real close friend. I thought he was dead at first, and that scared the hell out of me. It made my heart stop cold, made me feel like, just for a moment, my whole world was shattered." Rex grabbed one elbow in an oddly vulnerable gesture. "Turns out he was okay, made it just fine, but it made me re-think on what exactly..." He waved his hands helplessly and looked pleadingly at Dexter, who chuckled.

"I understand," he said. "That sounds like it could very well be the trigger for all this."

"But why?" asked Rex, looking down at his hands and flexing them slowly. "Why would something like that cause an overload of adrenaline and complete insomnia?"

"I can't pretend to know anything significant about your nanites, Rex, you would be better asking Doctor Holiday about that. But since you seem adamant on leaving her out of this..." Dexter trailed off and tapped his chin thoughtfully. "I would hazard a guess that your body is reacting to this new development of yours and as a result is keeping you alert and awake so you can be the first on scene should your friend get into trouble once more and perhaps save him from getting hurt."

"So how do I switch it off?"

"That I cannot say." The red-head arched an eyebrow and quirked a grin at the Evo. "I would suggest talking to him about this and see if you can't resolve your... one-sided issues."

Rex groaned and buried his head in his hands, and Ben moved over to him and put an arm around the older boy's shoulders in a comforting gesture. One dark red-brown eye peered at him through a gap in his elbow before it vanished, and Ben couldn't surpress a small smile.

Dexter nodded to them both. "Come back and see me if your condition persists. Goodnight Benjamin, Rex."

"Night," was chorused in return, and the boy genius vanished out the room. Silence reigned heavily for several minutes, neither of the remaining boys moving.

Eventually though Rex disentangled himself from Ben's admittedly warm embrace, sliding off the bench and walking to the door.

"Rex."

Ben's voice stopped him with a flinch, and he turned slowly to face a calculating green gaze. "I was the only one in that battle who got that badly hurt. What was all that about?"

"Nothing." Rex refused to meet Ben's eyes, and the teenager made an exasperated noise.

"Nothing my foot! It's thrown you and your nanites into complete turmoil! What on earth-"

He was cut off by a sound of frustrated longing and the next second he found himself pushed against the nearest wall, held there by a firm hand on his stomach and the other of the Evo's arms bracing Rex himself above the Omnitrix wielder's head.

There was so much in Rex's expression; confusion, longing, hurt, fear, but the emotion that stood out to Ben the most was lust. Mahogany eyes had darkened nearly to black, like the glowing embers of a recently put-out fire, and Ben felt anything he might have said get stuck in his throat. It was so obvious now what Rex wanted.

And it instantly became just as obvious that Ben wasn't going to stop him.

A tilt of the head and a slight tightening of the fingers still pressing Ben against the wall were the only warnings the brunette got before he found his lips locked with the older teen's.

It wasn't like it was unexpected, but the surprised noise he made was at their feel. The kiss was like nothing he'd ever shared with Julie; Rex's lips were chapped, worn, unglossed, more demanding. And Ben was happy to oblige. He slipped an arm around the back of Rex's head to bring him closer, and his other hand twisted into the Evo's jacket.

Rex made a noise of pleasure, putting more pressure into the kiss and letting the hand that had been pinning Ben to the wall loosen and map out a firm, lean stomach, lightly tracing along an invisible abdominal line. Ben rewarded the touch by parting his lips, allowing Rex to deepen their liplock and start up a dance with his own tongue. Rather than a dominance battle as the brunette had expected, the kiss was a lazy, contented waltz of tongues, gentle strokes carefully mapping out every inch of Ben's mouth and he gasped at the sensation.

Let it never be said that Rex Salazar wasn't a good kisser.

As their kiss came to a reluctant end the Evo withdrew with a couple more short, chaste kisses but never let their faces get far apart. "Now do you understand, Benji? You scared the shit out of me the other week. I won't let it happen again."

"It's the risk we all take, Rex," replied Ben softly, unclenching his fist from the other's jacket and bringing up to rest lightly on one cheek. "I can take care of myself; what happened that day was a fluke. I took that blow for Numbuh One because I knew I could survive it. I wasn't sure he could."

"I don't care! I thought-" Rex closed his eyes and gritted his teeth together. "I hate this war."

"So do I."

The Evo gave Ben a watery smile, one which was returned whole-heartedly and with another quick kiss. They slid to the floor together, Rex embracing the younger boy and burying his head on a green-clad shoulder. A comfortable silence settled around them, one that both were loathe to break.

After about five or ten minutes though, Rex did. "Ben?" he said, voice sounding far away and _tired_.

"Yeah?"

"I think that exhaustion is finally catching up."

"Then sleep," Ben prodded, tightening his hold on the Hispanic boy. "I'll be here when you wake, I promise."

"Thanks." Rex mumbled something else, but it was lost as the waves of sleep he had been so deprived of lately finally crashed down on him and sent him swirling into dreamland. Ben smiled and continued to hold Rex for several more minutes, before sighing and reaching around for his Omnitrix. Twiddling the dial and finding the right alien, he pushed down on it and a very familiar green glow enveloped his body.

'_Big Chill._'

The Necrofriggian picked up the slumbering dark-haired boy with ease, and turned them both intangible as he left the lab. He carried on to his own room; Rex wouldn't mind waking up there.

And Ben would be waiting when he did. He'd promised, after all.

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><p><strong>Rae:<strong> ...I warned you. :L R and R? x


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